AB1202 ASSESSMENT OF PAIN THRESHOLDS TO VERIFY CENTRAL SENSITIZATION IN PATIENTS WITH RHEUMATOID ARTHRITIS AND OSTEOARTHRITIS OF THE KNEE
Authors: E. Filatova
Journal: Annals of the Rheumatic Diseases (2022)

Background Central sensitization in patients with rheumatoid arthritis, osteoarthritis of the knees increases the risk of comorbid disorders, the most frequent of which are depression, cognitive impairment and insomnia. Verification and timely diagnosis of central sensitization will help to improve pain control in rheumatic diseases. (1,2) Objectives to study pressure pain thresholds in patients with rheumatoid arthritis (RA) and osteoarthritis of the knee (OAk) with chronic pain. Methods All patients had pain intensity scores according to the VAS scale, neuropathic/nocytoplastic pain severity according to the DN4 and Pain DETET questionnaires, central sensitization severity was assessed using the CSI scale. To verify the presence of central sensitization instrumentally and to confirm the presence of secondary hyperalgesia detected clinically, algometry was performed in 42 female patients with OAk and 42 patients with RA. A comparison group of 42 healthy volunteers comparable in gender and age with the patients was also selected. Using a Wagner FDK20 algometer, pressure pain thresholds for OAk in the knee joints were studied (4 points: 1st point located 2.5 cm medial to the patella, 2nd point in the center of the patella, 3rd 2.5 cm distal to the patella, 4th in the goosefoot area) and m. Trapezius (5th reference point) in all patients with OAC and controls. In the group with RA, pain thresholds were studied at 4 points: 1st - nail bed of the 1st finger, 2nd - wrist (above the extensor tendon retention), 3rd - 2.5 cm lateral to the kneecap and 4th m. trapezius (reference point) in all patients and controls. Results The mean age of patients with RA and OAk was 53.0 [41.0;61.0] and 61.0[57.0;63.0] years, with disease duration at the time of study of 9.0 [4.0;13.0] and 13.0[7.0;15.0] years, respectively. The DN4 questionnaire scores were 2.0 [1.0;4.0] for RA and 5.0[5.0;6.0] for OAk, and the Pain DETECT scores were 9.0[4.0;15.0] for RA and 17.0[14.0;19.0] for OAk. Pain intensity on VAS in patients was 60.0[40.0;70.0] for RA and 70.0[60.0;80.0] for OAk. The results of algometry are shown in Figure 1. Figure 1. Lower pain thresholds in patients with RA and OAk were noted not only in the area of the affected joints, but also in the distant reference point, indicating the presence of secondary hyperalgesia in these patients, which is a neurophysiological sign of central sensitization. A significant decrease in the pain threshold index was also noted in patients with central sensitization compared to those in the control groups. Conclusion The study of pain thresholds is one of the tools for verification of CS in patients with RA and OAk, but requires further study. References [1]Filatova E.S., Lila A.M. Contribution of neurogenic mechanisms to the pathogenesis of chronic joint pain. Modern Rheumatology Journal. 2021;15(2):43-49. (In Russ.) https://doi.org/10.14412/1996-7012-2021-2-43-49 [2]Smart KM, Blake C, Staines A, Doody C. Self-reported pain severity, quality of life, disability, anxiety and depression in patients classified with “nociceptive,” “peripheral neuropathic” and “central sensitisation” pain. The discriminant validity of mechanisms-based classifications of low back (±leg) pain // Manual Ther. – 2012. – Vol.17. – P. 119-125. Disclosure of Interests None declared